A Breakthrough in Zika Research Could Mean a Treatment for Pregnant Women

A newly-discovered antibody helped protect pregnant mice's fetuses.

For the last year, researchers have been hard at work rapidly developing a vaccine against Zika. But what about people who get infected before they've had a chance to be vaccinated? A newly-identified human antibody could offer protection for these people, particularly pregnant women, according to research published Monday in Nature.

When someone is infected with Zika, they become immune to the virus because their body fights it off and generates antibodies to protect against future infections. Vaccines work by stimulating the body to generate these antibodies before an infection, but researchers at Vanderbilt University Medical Center and Washington University School of Medicine also wanted to see if antibodies could help stop the spread of infection after the fact.

To do this, they took samples of blood from eight people who had been infected with different strains of Zika all over the world. Then they tested that blood for antibodies that could fend off the virus. They found a few, but one in particular—called ZIKV-117—stood out because it was able to defend against every strain of Zika, according to the study. They then took mice that had been injected with a mouse version of the Zika virus and gave them a dose of the antibody. They found that the antibody was able to stop the virus from spreading, even when there was a five day gap between the virus infection and the antibody treatment.

But the most notable part of the study was when researchers tested out the antibody on pregnant mice. Most people who get Zika don't have any symptoms, and if they do it's just a mild flu-like illness. But Zika can cause microcephaly—a birth defect where a child is born with a smaller than average head, which can hinder brain development—so pregnant women are a great concern in this outbreak. But when pregnant mice were treated with the ZIKV-117 antibody, it not only reduced the infection in the mother mouse, but it also protected the fetus from infection.

Of course, mice aren't people so it's not exactly like we have a cure for Zika about the hit the shelves next week. There are also still questions about the window of time when treatments like this would be most effective. Studies show fetuses are most at risk if the mother gets infected during the first trimester, but what if you aren't aware you're pregnant? Or you don't know you're at risk for Zika? When would a treatment like this be too late?

But these promising results mean researchers can keep testing the ZIKV-117 antibody in other animals, like primates, and hopefully get closer to a treatment that can help unvaccinated mothers before it's too late.